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Nanocomposite Membranes in Water Treatment
Published in P.K. Tewari, Advanced Water Technologies, 2020
The wetting properties of CNT determine which liquid will fill the tube by capillary action and cover the inner surface. The Young–Laplace equation relates the pressure difference (∆P) across the liquid–vapor interface in a capillary to the surface tension of the liquid and the contact angle between solid and liquid:ΔP=2γr−1cosθwhere r is the radius of curvature of the meniscus. The contact angle θ is an indicator of the strength of the interaction between the liquid and the solid interface relative to the cohesive forces in the liquid. If θ is smaller than 90°, the contact between the liquid and the surface is said to be wetting and ∆P is positive. Therefore, liquid will be pulled into the capillary spontaneously as there is an energy gain in the wetting process. If θ is greater than 90°, the contact angle is said to be nonwetting and ∆P will be negative. Therefore, when θ > 90°, the only way to introduce liquid into a capillary is to apply pressure larger than (∆P).
Five Methods for Humidification of Sweet Potato Stem-Cuttings
Published in Mark Anglin Harris, Confronting Global Climate Change, 2019
where the total evaporation E depends on the wetted height h and the evaporation rate e (per unit area) is established by the microenvironment (Hall and Hoff 2007). Thus in contrast to the system of Harris (2015), the reduced height of the column h in H2 of the present study decreased the total evaporation observed for H2 by at least 50%. This change was determined partially by the Young–Laplace equation, which describes the upward force of capillary pressure. A common variation of that capillary pressure equation is as follows: Pc=2γcosθ/rc
Representation of Solid-Liquid-Vapor Phase Interactions
Published in Satish G. Kandlikar, Masahiro Shoji, Vijay K. Dhir, Handbook of Phase Change: Boiling and Condensation, 2019
Masahiro Shoji, Yasuhiko H. Mori, Shigeo Maruyama
In both macroscopic and microscopic representations, the approach starts from the liquid-vapor interaction and the surface tension. The well-known Young-Laplace equation [Eq. (2.2-1)] relates the curvature of liquid-vapor interface and surface tension to the pressure difference called capillary pressure. From the equation, it is possible to obtain the geometry of the interface once the pressure term is prescribed. The microscopic representation of the Young-Laplace equation is used in the next section for the evaluation of the surface tension, which should be the kinetic property derived from the molecular parameters. Another example of the capability of the macroscopic representation is the gravitational deformation of a liquid droplet or a curved interface. The effect of gravity can be expressed using the capillary length a. When the system size is much smaller than a, the gravitational effect is negligible. No counterpart of the microscopic representation is possible, since the system size that the molecular dynamics method can handle is too small to show the effect, or, in other words, the system length scale L is always much smaller than the capillary length. In relation to the macroscopic representation, one of the hot arguments in molecular dynamics study is the determination of the condensation coefficient, which will be discussed here.
Numerical investigation of temperature increment effect on bubble dynamics in stagnant water and Al2O3 nanofluid column
Published in Particulate Science and Technology, 2018
Hamed Gharedaghi, Ahmad Dousti, Pedram Hanafizadeh, Mehdi Ashjaee
Another important numerical method for prediction of bubble dynamics is the Young–Laplace equation that used in the present work. Several theoretical works (Mori and Baines 2001; Gerlach et al. 2005; Vafaei, Borca-Tasciuc, and Wen 2010; Yakhshi-Tafti, Kumar, and Cho 2011; Vafaei, Chinnathambi, and Borca-Tasciuc 2015) utilized the Young–Laplace equation. Lesage, Cotton, and Robinson (2013) applied the Young–Laplace equation to predict the vapor bubble shape during the growth cycle. Gerlach et al. (2005) studied air bubbles formation from a submerged orifice based on the force balance principles. They used Young–Laplace equation for prediction of bubble characteristics. Moreover, they performed some experiments for verification of numerical results.